Give it up. A conical projectile would be too skimpy for the diameter it would have to be (much less mass than a corresponding rod or needle of the same diameter). There is no advantage to imparting spin, when the angular momentum would be vanishingly small, and "spiral dents" would only impair the physical integrity of the projectile (ice). Flechette rounds have been shot from guns for decades, and an ice flechette would be straightforward.
Good try, but insufficient to preclude a working design. You make too many assumptions. But let's check. You don't actually estimate a volume for the ice "needle" but let us suppose a frontal area of 4 square millimeters and a length of 20 millimeters = 80 cubic millimeters = 0.08 cubic centimeter => 0.08 gram (water ice density ~ 1 gram/cc). Muzzle velocity is not limited so much by energy as by the expansion process, so a muzzle velocity of 150 m/sec is not unreasonable. This is where the sabot comes in, which would provide some mass to moderate the acceleration and structural support for the needle. (There is no shock wave inside an air pistol.) It would aerodynamically peel away once free of the muzzle.
A muzzle velocity of 150 m/sec would equate to 500 fps, or 340 mph, so stick your hand outside the window of your car at that speed and encounter a particle of hail and see if it penetrates. Something pointed would penetrate just fine. Arrows travel at 100 to 300 fps and penetrate most regularly. (I once pounded my fist against an interior wall and discovered I had been penetrated by a nail head. Never noticed it, and I can bet you my fist was not traveling anything close to 340 mph.)
The scope is not B.S. Ever shot a target at 50 feet? Even a 2x scope would come in handy for fine work. Having a reticle zeroed to the weapon would be a lot better than a standard pair of sights. (Why you would scorn something that would improve your aim suggests to me you are not cut out to be an assassin. But that's not a bad thing.)
So, the minimum perforation velocity does not seem to be a problem, and there is no minimum mass limitation if a sabot is used (as it surely would have to be in order to maintain support for the needle and avoid wear/tear against the gun barrel). It looks credible upon analysis.
Give it up. A conical projectile would be too skimpy for the diameter it would have to be (much less mass than a corresponding rod or needle of the same diameter). There is no advantage to imparting spin, when the angular momentum would be vanishingly small, and "spiral dents" would only impair the physical integrity of the projectile (ice). Flechette rounds have been shot from guns for decades, and an ice flechette would be straightforward.
Good try, but insufficient to preclude a working design. You make too many assumptions. But let's check. You don't actually estimate a volume for the ice "needle" but let us suppose a frontal area of 4 square millimeters and a length of 20 millimeters = 80 cubic millimeters = 0.08 cubic centimeter => 0.08 gram (water ice density ~ 1 gram/cc). Muzzle velocity is not limited so much by energy as by the expansion process, so a muzzle velocity of 150 m/sec is not unreasonable. This is where the sabot comes in, which would provide some mass to moderate the acceleration and structural support for the needle. (There is no shock wave inside an air pistol.) It would aerodynamically peel away once free of the muzzle.
A muzzle velocity of 150 m/sec would equate to 500 fps, or 340 mph, so stick your hand outside the window of your car at that speed and encounter a particle of hail and see if it penetrates. Something pointed would penetrate just fine. Arrows travel at 100 to 300 fps and penetrate most regularly. (I once pounded my fist against an interior wall and discovered I had been penetrated by a nail head. Never noticed it, and I can bet you my fist was not traveling anything close to 340 mph.)
The scope is not B.S. Ever shot a target at 50 feet? Even a 2x scope would come in handy for fine work. Having a reticle zeroed to the weapon would be a lot better than a standard pair of sights. (Why you would scorn something that would improve your aim suggests to me you are not cut out to be an assassin. But that's not a bad thing.)
So, the minimum perforation velocity does not seem to be a problem, and there is no minimum mass limitation if a sabot is used (as it surely would have to be in order to maintain support for the needle and avoid wear/tear against the gun barrel). It looks credible upon analysis.